sbin/ddb/ddb_capture.c

   1 /*-
   2  * Copyright (c) 2008 Robert N. M. Watson
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  */
  26
  27 #include <sys/cdefs.h>
  28 __FBSDID("$FreeBSD$");
  29
  30 #include <sys/types.h>
  31 #include <sys/sysctl.h>
  32
  33 #include <err.h>
  34 #include <errno.h>
  35 #include <fcntl.h>
  36 #include <kvm.h>
  37 #include <limits.h>
  38 #include <stdio.h>
  39 #include <stdlib.h>
  40 #include <string.h>
  41 #include <sysexits.h>
  42 #include <unistd.h>
  43
  44 #include "ddb.h"
  45
  46 /*
  47  * Interface with the ddb(4) capture buffer of a live kernel using sysctl, or
  48  * for a crash dump using libkvm.
  49  */
  50 #define SYSCTL_DDB_CAPTURE_BUFOFF       "debug.ddb.capture.bufoff"
  51 #define SYSCTL_DDB_CAPTURE_BUFSIZE      "debug.ddb.capture.bufsize"
  52 #define SYSCTL_DDB_CAPTURE_MAXBUFSIZE   "debug.ddb.capture.maxbufsize"
  53 #define SYSCTL_DDB_CAPTURE_DATA         "debug.ddb.capture.data"
  54 #define SYSCTL_DDB_CAPTURE_INPROGRESS   "debug.ddb.capture.inprogress"
  55
  56 static struct nlist namelist[] = {
  57 #define X_DB_CAPTURE_BUF        0
  58         { .n_name = "_db_capture_buf" },
  59 #define X_DB_CAPTURE_BUFSIZE    1
  60         { .n_name = "_db_capture_bufsize" },
  61 #define X_DB_CAPTURE_MAXBUFSIZE 2
  62         { .n_name = "_db_capture_maxbufsize" },
  63 #define X_DB_CAPTURE_BUFOFF     3
  64         { .n_name = "_db_capture_bufoff" },
  65 #define X_DB_CAPTURE_INPROGRESS 4
  66         { .n_name = "_db_capture_inprogress" },
  67         { .n_name = "" },
  68 };
  69
  70 static int
  71 kread(kvm_t *kvm, void *kvm_pointer, void *address, size_t size,
  72     size_t offset)
  73 {
  74         ssize_t ret;
  75
  76         ret = kvm_read(kvm, (unsigned long)kvm_pointer + offset, address,
  77             size);
  78         if (ret < 0 || (size_t)ret != size)
  79                 return (-1);
  80         return (0);
  81 }
  82
  83 static int
  84 kread_symbol(kvm_t *kvm, int index, void *address, size_t size,
  85     size_t offset)
  86 {
  87         ssize_t ret;
  88
  89         ret = kvm_read(kvm, namelist[index].n_value + offset, address, size);
  90         if (ret < 0 || (size_t)ret != size)
  91                 return (-1);
  92         return (0);
  93 }
  94
  95 static void
  96 ddb_capture_print_kvm(kvm_t *kvm)
  97 {
  98         u_int db_capture_bufoff;
  99         char *buffer, *db_capture_buf;
 100
 101         if (kread_symbol(kvm, X_DB_CAPTURE_BUF, &db_capture_buf,
 102             sizeof(db_capture_buf), 0) < 0)
 103                 errx(-1, "kvm: unable to read db_capture_buf");
 104
 105         if (kread_symbol(kvm, X_DB_CAPTURE_BUFOFF, &db_capture_bufoff,
 106             sizeof(db_capture_bufoff), 0) < 0)
 107                 errx(-1, "kvm: unable to read db_capture_bufoff");
 108
 109         buffer = malloc(db_capture_bufoff + 1);
 110         if (buffer == NULL)
 111                 err(-1, "malloc: db_capture_bufoff (%u)",
 112                     db_capture_bufoff);
 113         bzero(buffer, db_capture_bufoff + 1);
 114
 115         if (kread(kvm, db_capture_buf, buffer, db_capture_bufoff, 0) < 0)
 116                 errx(-1, "kvm: unable to read buffer");
 117
 118         printf("%s\n", buffer);
 119         free(buffer);
 120 }
 121
 122 static void
 123 ddb_capture_print_sysctl(void)
 124 {
 125         size_t buflen, len;
 126         char *buffer;
 127         int ret;
 128
 129 repeat:
 130         if (sysctlbyname(SYSCTL_DDB_CAPTURE_DATA, NULL, &buflen, NULL, 0) < 0)
 131                 err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_DATA);
 132         if (buflen == 0)
 133                 return;
 134         buffer = malloc(buflen);
 135         if (buffer == NULL)
 136                 err(EX_OSERR, "malloc");
 137         bzero(buffer, buflen);
 138         len = buflen;
 139         ret = sysctlbyname(SYSCTL_DDB_CAPTURE_DATA, buffer, &len, NULL, 0);
 140         if (ret < 0 && errno != ENOMEM)
 141                 err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_DATA);
 142         if (ret < 0) {
 143                 free(buffer);
 144                 goto repeat;
 145         }
 146
 147         printf("%s\n", buffer);
 148         free(buffer);
 149 }
 150
 151 static void
 152 ddb_capture_status_kvm(kvm_t *kvm)
 153 {
 154         u_int db_capture_bufoff, db_capture_bufsize, db_capture_inprogress;
 155
 156         if (kread_symbol(kvm, X_DB_CAPTURE_BUFOFF, &db_capture_bufoff,
 157             sizeof(db_capture_bufoff), 0) < 0)
 158                 errx(-1, "kvm: unable to read db_capture_bufoff");
 159         if (kread_symbol(kvm, X_DB_CAPTURE_BUFSIZE, &db_capture_bufsize,
 160             sizeof(db_capture_bufsize), 0) < 0)
 161                 errx(-1, "kvm: unable to read db_capture_bufsize");
 162         if (kread_symbol(kvm, X_DB_CAPTURE_INPROGRESS,
 163             &db_capture_inprogress, sizeof(db_capture_inprogress), 0) < 0)
 164                 err(-1, "kvm: unable to read db_capture_inprogress");
 165         printf("%u/%u bytes used\n", db_capture_bufoff, db_capture_bufsize);
 166         if (db_capture_inprogress)
 167                 printf("capture is on\n");
 168         else
 169                 printf("capture is off\n");
 170
 171 }
 172
 173 static void
 174 ddb_capture_status_sysctl(void)
 175 {
 176         u_int db_capture_bufoff, db_capture_bufsize, db_capture_inprogress;
 177         size_t len;
 178
 179         len = sizeof(db_capture_bufoff);
 180         if (sysctlbyname(SYSCTL_DDB_CAPTURE_BUFOFF, &db_capture_bufoff, &len,
 181             NULL, 0) < 0)
 182                 err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_BUFOFF);
 183         len = sizeof(db_capture_bufoff);
 184         if (sysctlbyname(SYSCTL_DDB_CAPTURE_BUFSIZE, &db_capture_bufsize,
 185             &len, NULL, 0) < 0)
 186                 err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_BUFSIZE);
 187         len = sizeof(db_capture_inprogress);
 188         if (sysctlbyname(SYSCTL_DDB_CAPTURE_INPROGRESS,
 189             &db_capture_inprogress, &len, NULL, 0) < 0)
 190                 err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_INPROGRESS);
 191         printf("%u/%u bytes used\n", db_capture_bufoff, db_capture_bufsize);
 192         if (db_capture_inprogress)
 193                 printf("capture is on\n");
 194         else
 195                 printf("capture is off\n");
 196 }
 197
 198 void
 199 ddb_capture(int argc, char *argv[])
 200 {
 201         char *mflag, *nflag, errbuf[_POSIX2_LINE_MAX];
 202         kvm_t *kvm;
 203         int ch;
 204
 205         mflag = NULL;
 206         nflag = NULL;
 207         kvm = NULL;
 208         while ((ch = getopt(argc, argv, "M:N:")) != -1) {
 209                 switch (ch) {
 210                 case 'M':
 211                         mflag = optarg;
 212                         break;
 213
 214                 case 'N':
 215                         nflag = optarg;
 216                         break;
 217
 218                 default:
 219                         usage();
 220                 }
 221         }
 222         argc -= optind;
 223         argv += optind;
 224
 225         if (argc != 1)
 226                 usage();
 227
 228         if (mflag != NULL) {
 229                 kvm = kvm_openfiles(nflag, mflag, NULL, O_RDONLY, errbuf);
 230                 if (kvm == NULL)
 231                         errx(-1, "ddb_capture: kvm_openfiles: %s", errbuf);
 232                 if (kvm_nlist(kvm, namelist) != 0)
 233                         errx(-1, "ddb_capture: kvm_nlist");
 234         } else if (nflag != NULL)
 235                 usage();
 236         if (strcmp(argv[0], "print") == 0) {
 237                 if (kvm != NULL)
 238                         ddb_capture_print_kvm(kvm);
 239                 else
 240                         ddb_capture_print_sysctl();
 241         } else if (strcmp(argv[0], "status") == 0) {
 242                 if (kvm != NULL)
 243                         ddb_capture_status_kvm(kvm);
 244                 else
 245                         ddb_capture_status_sysctl();
 246         } else
 247                 usage();
 248 }